This invention relates to a process for closing flexible containers and to the closure produced by such a process. It particularly relates to a closure which not only maintains the contents of a container within the container but also prevents the ingress of deleterious atmosphere into the container.
It is known in the art, to close flexible containers with different types of complicated assemblies in which various parts are required. U.S. Pat. No. 3,308,936 to Roland features the use of a metallic cap disposed over the opening of a flexible container with a sealant adhering the metallic cap to the container itself. U.S. Pat. No. 3,317,119 to Lasoff discloses a plastic retaining ring which encircles the twisted neck of a flexible container. U.S. Pat. No. 3,197,938 shows a similar construction for a flexible container closure. Another approach to the problem is disclosed in U.S. Pat. No. 3,111,794 to Spolsino. This patent discloses a process for sealing a flexible container composed of a thermoplastic material by first clipping the opening of the flexible container and subsequently heating the gathered portion near the clip to melt and adhere the gathered material to itself.
While all of the above mentioned processes and closures are satisfactory for most applications, room exists for improving the aesthetics, reliability and production efficiency of such processes and closures. The realibility of closures for flexible containers is particularly critical when the container is designed for protecting food articles such as fresh meat from the deleterious effects of the surrounding environment. In such instances the closure for the flexible container must be efficacious not only from the standpoint of closing the container but also from the standpoint of preventing ingress of deleterious atmosphere into the closed container. In instances where the food article is intended for a subsequent freezing step, the container closure must be able to retain its reliability after being subjected to a freezing and thawing environment.